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Structural Framework (structural + framework)
Selected AbstractsToward Effective Chiral Catalysts Containing the N,P=O Structural Framework for the Borane-Mediated Asymmetric Reduction of Prochiral Ketones.CHEMINFORM, Issue 43 2004Deevi Basavaiah Abstract For Abstract see ChemInform Abstract in Full Text. [source] The Impact of Uncertainty ShocksECONOMETRICA, Issue 3 2009Nicholas Bloom Uncertainty appears to jump up after major shocks like the Cuban Missile crisis, the assassination of JFK, the OPEC I oil-price shock, and the 9/11 terrorist attacks. This paper offers a structural framework to analyze the impact of these uncertainty shocks. I build a model with a time-varying second moment, which is numerically solved and estimated using firm-level data. The parameterized model is then used to simulate a macro uncertainty shock, which produces a rapid drop and rebound in aggregate output and employment. This occurs because higher uncertainty causes firms to temporarily pause their investment and hiring. Productivity growth also falls because this pause in activity freezes reallocation across units. In the medium term the increased volatility from the shock induces an overshoot in output, employment, and productivity. Thus, uncertainty shocks generate short sharp recessions and recoveries. This simulated impact of an uncertainty shock is compared to vector autoregression estimations on actual data, showing a good match in both magnitude and timing. The paper also jointly estimates labor and capital adjustment costs (both convex and nonconvex). Ignoring capital adjustment costs is shown to lead to substantial bias, while ignoring labor adjustment costs does not. [source] Molecular interaction of neutral trehalase with other enzymes of trehalose metabolism in the fission yeast Schizosaccharomyces pombeFEBS JOURNAL, Issue 15 2002Teresa Soto Trehalose metabolism is an essential component of the stress response in yeast cells. In this work we show that the products of the principal genes involved in trehalose metabolism in Schizosaccharomyces pombe, tps1+ (coding for trehalose-6- P synthase, Tps1p), ntp1+ (encoding neutral trehalase, Ntp1p) and tpp1+ (that codes for trehalose-6- P phosphatase, Tpp1p), interact in vitro with each other and with themselves to form protein complexes. Disruption of the gene tps1+ blocks the activation of the neutral trehalase induced by heat shock but not by osmotic stress. We propose that this association may reflect the Tps1p-dependent requirement for thermal activation of trehalase. Data reported here indicate that following a heat shock the enzyme activity of trehalase is associated with Ntp1p dimers or trimers but not with either Ntp1p monomers or with complexes involving Tps1p. These results raise the possibility that heat shock and osmotic stress activate trehalase differentially by acting in the first case through an specific mechanism involving Tps1p,Ntp1p complexes. This study provides the first evidence for the participation of the catabolic enzyme trehalase in the structural framework of a regulatory macromolecular complex containing trehalose-6- P synthase in the fission yeast. [source] From the intra-desert ridges to the marine carbonate island chain: middle to late Permian (Upper Rotliegend,Lower Zechstein) of the Wolsztyn,Pogorzela high, west PolandGEOLOGICAL JOURNAL, Issue 2-3 2010Hubert Kiersnowski Abstract The tectonic Wolsztyn,Pogorzela palaeo-High (WPH) is the south-eastern termination of the Brandenburg,Wolsztyn High (western Poland), which during Late Permian times was an intra-basin ridge surrounded by Upper Rotliegend sedimentary basins within the Southern Permian Basin. The geological history and structural framework of the WPH are complex. The High belongs to the Variscan Externides, consisting at present of strongly folded, faulted and eroded Viséan to Namurian flysch deposits capped by a thick cover of Upper Carboniferous,Lower Permian volcanic rocks. This sedimentary-volcanic complex was strongly fragmented and vertically differentiated by tectonic movements and subsequently eroded, resulting in the deposition of coarse clastics surrounding uplifted tectonic blocks. During late Rotliegend time, arid climatic conditions significantly influenced occurrences of specific facies assemblages: alluvial, fluvial, aeolian and playa. Sedimentological study helped to recognize the interplay of tectonic and palaeoclimatic factors and to understand the phenomenon of aeolian sandstones interbedded with coarse deposits of alluvial cones close to fault scarps. Subsequent tectonic and possible thermal subsidence of the studied area was synchronous with inundation by the Zechstein Sea. The rapid inundation process allowed for the preservation of an almost perfectly protected Uppermost Rotliegend landscape. Based on 3D seismic data from the base Zechstein reflector, a reconstruction of Rotliegend palaeogeomorphology was carried out, which shows examples of tectonic rejuvenation of particular tectonic blocks within the WPH area before inundation by the Zechstein Sea. The inundation led to the deposition of the marine Kupferschiefer Shale followed by the Zechstein Limestone. In the deeper parts of the basin the latter is developed in thin basinal facies: in shallow parts (e.g. uplifted tectonic blocks forming in some cases islands), carbonate buildups were formed. The remarkable thickness of those buildups (bryozoan reefs) is interpreted as due to stable tectonic subsidence together with a rise of sea level. A detailed study of carbonate buildups has showed that their internal structure reflects changes in shallow marine environments and even emersion events, caused by sea-level oscillations and tectonic movements of the reef substrate. Copyright © 2010 John Wiley & Sons, Ltd. [source] Triassic metasedimentary successions across the boundary between the southern Apennines and the Calabrian Arc (northern Calabria, Italy)GEOLOGICAL JOURNAL, Issue 2 2005A. Iannace Abstract The boundary area between the Apenninic fold-and-thrust belt and the crystalline Calabrian Arc, located around Sangineto in northern Calabria, has been investigated. New geological mapping in the Sant'Agata area has been performed on the Triassic successions traditionally attributed to the metasedimentary San Donato Unit. This, coupled with a reappraisal of the stratigraphy and tectonics of coeval successions present more to the south in the Cetraro Unit, results in a new reconstruction of the Triassic evolution of all the metasedimentary successions found in the region. Four informal stratigraphic units have been distinguished in the S. Agata area. The lowest one (Unit A) consists of well-bedded metalimestones and bioturbated marly limestones that correlate with Ladinian,Carnian carbonates in nearby areas. A second unit (Unit B), never recognized before, contains a complex alternation of dolomites, phyllites and some meta-arenites containing several beds of Cavernoso facies, attributed to the Carnian. They grade upward to platform and platform-margin dolomites of Norian,Rhaetian age (Unit C) that in turn are replaced upward and laterally by a fourth unit (Unit D) consisting of well-bedded, dark dolomites and metalimestones with marly interlayers locally found as resedimented large blocks in slope conglomerates. Unit D correlates with Rhaetian,Liassic beds in nearby areas. Several pieces of evidence of post-metamorphic contractional tectonics, with 140°N and 30°N trends, are found together with evidence of SW-directed extension. The siliciclastic Carnian beds of Unit B are correlated with the phyllites of Cetraro, formerly believed to be Middle Triassic; moreover, it is suggested that in the Cetraro area Unit C is almost totally replaced by Unit D. This demonstrates that the former distinction between the two tectonic units in the whole area has to be discarded. We have made a general palaeoenvironmental reconstruction which progresses laterally, during Ladinian,Carnian times, from (i) a coastal, mixed siliciclastic,carbonate,evaporitic area at Cetraro to (ii) a transitional carbonate shelf where siliciclastic input was only episodic, and finally to (iii) a bioconstructed margin which was later replaced by a steepened margin created by tectonic instability. Starting from the Norian, subsidence shifted toward the former coastal area where an intraplatform, restricted basin developed. The proposed stratigraphy corresponds closely to the Alpujarride units of the Betic Cordillera, Spain. Moreover, it is shown that strong affinities also exist, in terms of the structural framework, with the metamorphic units of Tuscany and Liguria. Copyright © 2005 John Wiley & Sons, Ltd. [source] Schwann cell caveolin-1 expression increases during myelination and decreases after axotomyGLIA, Issue 3 2002Daniel D. Mikol Abstract The caveolins are a family of related proteins that form the structural framework of caveolae. They have been implicated in the regulation of signal transduction, cell cycle control, and cellular transport processes, particularly cholesterol trafficking. Caveolin-1 is expressed by a variety of cell types, including Schwann cells, although its expression is greatest in differentiated cell types, such as endothelial cells and adipocytes. In the present work, we characterize caveolin-1 expression both during rat sciatic nerve development and after axotomy. Schwann cells express little caveolin-1 on postnatal days 1 and 6. By P30, myelinating Schwann cells express caveolin-1, which is localized in the outer/abaxonal myelin membranes as well as intracellularly. After axotomy, Schwann cell caveolin-1 expression in the distal nerve stump decreases as Schwann cells revert to a premyelinating (p75-positive) phenotype; residual caveolin-1 within the nerve largely localizes to myelin debris and infiltrating macrophages. We speculate that caveolin-1 plays a role in the biology of myelinating Schwann cells. GLIA 38:191,199, 2002. © 2002 Wiley-Liss, Inc. [source] Subcellular distribution of key enzymes of lipid metabolism during the euthermia-hibernation-arousal cycleJOURNAL OF ANATOMY, Issue 6 2009Anna Suozzi Abstract Mammalian hibernation is a natural, fully reversible hypometabolic state characterized by a drastic reduction of body temperature and metabolic activity, which ensures survival to many species under adverse environmental conditions. During hibernation, many hibernators rely for energy supply almost exclusively on lipid reserves; the shift from carbohydrate to lipid metabolism implies profound rearrangement of the anabolic and catabolic pathways of energetic substrates. However, the structural counterpart of such adaptation is not known. In this study we investigated, by using immunoelectron microscopy, the fine intracellular distribution of two key enzymes involved in lipid metabolism, namely, the fatty acid synthase (FAS) and the long-chain fatty acyl-CoA synthetase (ACSL), in hepatocytes of euthermic, hibernating and arousing hazel dormice. Our results show that the two enzymes are differentially distributed in cellular compartments (cytoplasm, mitochondria and cell nuclei) of hepatocytes during euthermia. Quantitative redistribution of both enzymes among cellular compartments takes place during hibernation and arousal, in accordance with the physiological changes. Interestingly, this redistribution follows different seasonal patterns in cytoplasm, mitochondria and nuclei. In conclusion, our data represent the first quantitative morphological evidence of lipid enzyme distribution in a true hibernator throughout the year cycle, thus providing a structural framework to biochemical changes associated with the hypometabolism of hibernation. [source] Nuclear matrix proteins as biomarkers in prostate cancerJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2002Eddy S. Leman Abstract The nuclear matrix (NM) is the structural framework of the nucleus that consists of the peripheral lamins and pore complexes, an internal ribonucleic protein network, and residual nucleoli. The NM contains proteins that contribute to the preservation of nuclear shape and its organization. These protein components better known as the NM proteins have been demonstrated to be tissue specific, and are altered in many cancers, including prostate cancer. Alterations in nuclear morphology are hallmarks of cancer and are believed to be associated with changes in NM protein composition. Prostate cancer is the most frequently diagnosed cancer in American men and many investigators have identified unique NM proteins that appear to be specific for this disease. These NM protein changes are associated with the development of prostate cancer, as well as in some cases being indicative of cancer stage. Identification of these NM proteins specific for prostate cancer provides an insight to understanding the molecular changes associated with this disease. This article reviews the role of NM proteins as tumor biomarkers in prostate cancer and the potential application of these proteins as therapeutic targets in the treatment of this disease. J. Cell. Biochem. 86: 213,223, 2002. © 2002 Wiley-Liss, Inc. [source] Multinational supermarket chains in developing countries: does local agriculture benefit?AGRICULTURAL ECONOMICS, Issue 6 2009Hildegunn E. Stokke Backward productivity spillovers; Local constraints; Supply chain development; Intertemporal general equilibrium model Abstract There is no consensus in the empirical literature on how entry of multinational supermarket chains affects farmers in developing countries. Econometric analyses struggle with causality issues and are unclear about the channel of effects. We quantify the dynamic effects of supermarket expansion on agriculture within a structural framework that clarifies the adjustment mechanisms involved. The model specification allows for endogenous interaction between agricultural productivity and supermarkets' choice of suppliers. Based on numerical simulations, two results emerge. First, we offer a possible interpretation of the conflicting evidence in the empirical literature. Whether farmers benefit from supermarkets or get stuck in a low productivity trap depends on the extent of local constraints related to production capacity and market access. Second, supply chain development initiated by supermarkets can help farmers escape the low productivity trap. While supermarkets face a short-run cost to supplier upgrading, they gradually gain from more productive local suppliers. [source] Core competencies in hospital medicine: Development and methodologyJOURNAL OF HOSPITAL MEDICINE, Issue S1 2006Daniel D. Dressler MD Abstract BACKGROUND The hospitalist model of inpatient care has been rapidly expanding over the last decade, with significant growth related to the quality and efficiency of care provision. This growth and development have stimulated a need to better define and characterize the field of hospital medicine. Training and developing curricula specific to hospital medicine are the next step in the evolution of the field. METHODS The Core Competencies in Hospital Medicine: A Framework for Curriculum Development (the Core Competencies), by the Society of Hospital Medicine, introduces the expectations of hospitalists and provides an initial structural framework to guide medical educators in developing curricula that incorporate these competencies into the training and evaluation of students, clinicians-in-training, and practicing hospitalists. This article outlines the process that was undertaken to develop the Core Competencies, which included formation of a task force and editorial board, development of a topic list, the solicitation for and writing of chapters, and the execution of multiple reviews by the editorial board and both internal and external reviewers. RESULTS This process culminated in the Core Competencies document, which is divided into three sections: Clinical Conditions, Procedures, and Healthcare Systems. The chapters in each section delineate the core knowledge, skills, and attitudes necessary for effective inpatient practice while also incorporating a systems organization and improvement approach to care coordination and optimization. CONCLUSIONS These competencies should be a common reference and foundation for the creation of hospital medicine curricula and serve to standardize and improve inpatient training practices. Journal of Hospital Medicine 2006;1:48,56. © 2006 Society of Hospital Medicine. [source] RESERVOIR POTENTIAL OF A LACUSTRINE MIXED CARBONATE / SILICICLASTIC GAS RESERVOIR: THE LOWER TRIASSIC ROGENSTEIN IN THE NETHERLANDSJOURNAL OF PETROLEUM GEOLOGY, Issue 1 2008D. Palermo The Lower Triassic Rogenstein Member of the Buntsandstein Formation produces gas at the De Wijk and Wanneperveen fields, NE Netherlands and consists mainly of claystones with intercalated oolitic limestone beds. The excellent reservoir properties of the oolites (,= 20-30%; k = 5-4000 mD) are predominantly controlled by depositional facies. Oolitic limestones are interpreted as the storm and wave deposits of a shallow, desert lake located in the Central European Buntsandstein Basin. The vertical sequence of lithofacies in the Rogenstein Member indicates cyclic changes of relative lake level. The reservoir rock is vertically arranged in a three-fold hierarchy of cycles, recognised both in cores and wireline logs. These cycles are a key to understanding the distribution of reservoir facies, and are used as the basis for a high-resolution sequence stratigraphic correlation of the reservoir units. Slight regional-scale thickness variations of the Rogenstein Member (in the order of tens of metres) are interpreted as the effects of differential subsidence associated with the inherited Palaeozoic structural framework. The depositional basin can be subdivided into subtle palaeo-highs and -lows which controlled facies distribution during Rogenstein deposition. Oolitic limestones show their greatest lateral extent and thickest development in the Middle Rogenstein during large-scale maximum flooding. Potential reservoir rocks (decimetre to metres thick) are present in the NE Netherlands, in particular in the Lauwerszee Trough and the Lower Saxony Basin, where abundant gas shows of 200 - 4000 ppm CH4 have been recorded. Preserved primary porosity is interpreted to be a result of rapid burial in subtle depositional palaeo-lows in this area. The thickest, amalgamated oolite intervals (tens of metres thick) occur in the eastern part of the Central Netherlands Basin. Because of poor reservoir properties, other areas appear to be less promising in terms of Rogenstein exploration potential. [source] The role of ,-, 310 -, and ,-helix in helix,coil transitionsPROTEIN SCIENCE, Issue 6 2003Roger Armen Abstract The conformational equilibrium between 310 - and ,-helical structure has been studied via high-resolution NMR spectroscopy by Millhauser and coworkers using the MW peptide Ac-AMAAKAWAAKA AAARA-NH2. Their 750-MHz nuclear Overhauser effect spectroscopy (NOESY) spectra were interpreted to reflect appreciable populations of 310 -helix throughout the peptide, with the greatest contribution at the N and C termini. The presence of simultaneous ,N(i,i + 2) and ,N(i,i + 4) NOE cross-peaks was proposed to represent conformational averaging between 310 - and ,-helical structures. In this study, we describe 25-nsec molecular dynamics simulations of the MW peptide at 298 K, using both an 8 Å and a 10 Å force-shifted nonbonded cutoff. The ensemble averages of both simulations are in reasonable agreement with the experimental helical content from circular dichroism (CD), the 3JHN, coupling constants, and the 57 observed NOEs. Analysis of the structures from both simulations revealed very little formation of contiguous i , i + 3 hydrogen bonds (310 -helix); however, there was a large population of bifurcated i , i + 3 and i , i + 4 ,-helical hydrogen bonds. In addition, both simulations contained considerable populations of ,-helix (i , i + 5 hydrogen bonds). Individual turns formed over residues 1,9, which we predict contribute to the intensities of the experimentally observed ,N(i,i + 2) NOEs. Here we show how sampling of both folded and unfolded structures can provide a structural framework for deconvolution of the conformational contributions to experimental ensemble averages. [source] Structural study and thermodynamic characterization of inhibitor binding to lumazine synthase from Bacillus anthracisACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2010Ekaterina Morgunova The crystal structure of lumazine synthase from Bacillus anthracis was solved by molecular replacement and refined to Rcryst = 23.7% (Rfree = 28.4%) at a resolution of 3.5,Å. The structure reveals the icosahedral symmetry of the enzyme and specific features of the active site that are unique in comparison with previously determined orthologues. The application of isothermal titration calorimetry in combination with enzyme kinetics showed that three designed pyrimidine derivatives bind to lumazine synthase with micromolar dissociation constants and competitively inhibit the catalytic reaction. Structure-based modelling suggested the binding modes of the inhibitors in the active site and allowed an estimation of the possible contacts formed upon binding. The results provide a structural framework for the design of antibiotics active against B. anthracis. [source] Hydrocarbon Accumulation Conditions of Ordovician Carbonate in Tarim BasinACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2010LI Qiming Abstract: Based on comprehensive analysis of reservoir-forming conditions, the diversity of reservoir and the difference of multistage hydrocarbon charge are the key factors for the carbonate hydrocarbon accumulation of the Ordovician in the Tarim Basin. Undergone four major deposition-tectonic cycles, the Ordovician carbonate formed a stable structural framework with huge uplifts, in which are developed reservoirs of the reef-bank type and unconformity type, and resulted in multistage hydrocarbon charge and accumulation during the Caledonian, Late Hercynian and Late Himalayan. With low matrix porosity and permeability of the Ordovician carbonate, the secondary solution pores and caverns serve as the main reservoir space. The polyphase tectonic movements formed unconformity reservoirs widely distributed around the paleo-uplifts; and the reef-bank reservoir is controlled by two kinds of sedimentary facies belts, namely the steep slope and gentle slope. The unconventional carbonate pool is characterized by extensive distribution, no obvious edge water or bottom water, complicated oil/gas/water relations and severe heterogeneity controlled by reservoirs. The low porosity and low permeability reservoir together with multi-period hydrocarbon accumulation resulted in the difference and complex of the distribution and production of oil/gas/water. The distribution of hydrocarbon is controlled by the temporal-spatial relation between revolution of source rocks and paleo-uplifts. The heterogenetic carbonate reservoir and late-stage gas charge are the main factors making the oil/ gas phase complicated. The slope areas of the paleo-uplifts formed in the Paleozoic are the main carbonate exploration directions based on comprehensive evaluation. The Ordovician of the northern slope of the Tazhong uplift, Lunnan and its periphery areas are practical exploration fields. The Yengimahalla-Hanikatam and Markit slopes are the important replacement targets for carbonate exploration. Gucheng, Tadong, the deep layers of Cambrian dolomite in the Lunnan and Tazhong-Bachu areas are favorable directions for research and risk exploration. [source] Tectonic Constraints on the Transformation of Paleozoic Framework of Uplift and Depression in the Ordos AreaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 6 2006WANG Qingfei Abstract: During the Paleozoic, the Ordos area in the western North China Plate was located at the intersecting position of microplates and controlled by their interaction. The structural framework in the Ordos area, which underwent transformations in the Ordovician, the Carboniferous and the Permian respectively, was dominated by the alternation of uplift and depression. The transformations of structural framework are utilized as the clues to investigate the microplates' interacting type and its response in the Ordos area. According to the regional structural evolution, the Ordos area is simplified into an isopachous, isotropic and elastic shell model, and under proposed various boundary conditions, three series of numerical simulations corresponding to the three structural transformations are carried out to determine the detailed tectonic constraints. Numerical simulations reveal that the structure of the uplift and depression, which is similar to the actual pattern, develops only under one special boundary condition in each of the three series, indicating that the structural framework responds to the unique tectonic background. The simulation results show that in the Early Paleozoic, the L-shaped paleouplift formed nearby the southwestern corner of the Ordos area because the intensity of the compressions in the southern and western boundaries resulting from the ocean-continent collisions was similar. In the Late Paleozoic, it evolved into continent-continent (or arc-continent) interaction in the southern and northern boundaries; in the preliminary stage of the interaction, since the interface between the North China Plate and the plates on the south and north was narrow, the relative acting force was little and the regional western boundary immobile, and the structural framework in the basin was characterized by the N-S trending slender-waist,shaped uplift; as the interface between the plates expanded gradually, the extrusive force in the southern and northern boundaries of the North China Plate increased, resulting in the paleogeographic divisions showing E-W trending, and, the western boundary of the basin was extruded westward due to the intense compression inducing the local NE trending of paleogeographic division in the central area. The simulation results further reflect that the symmetry of the uplift-depression pattern is restricted by that of the boundary conditions, suggesting that the Paleozoic structural transformations of the Ordos area under boundary constraints accord with the universal physical symmetrical principle. [source] Regulatory mechanisms and functions of intermediate filaments: A study using site- and phosphorylation state-specific antibodiesCANCER SCIENCE, Issue 3 2006Ichiro Izawa Intermediate filaments (IF) form the structural framework of the cytoskeleton. Although histopathological detection of IF proteins is utilized for examining cancer specimens as reliable markers, the molecular mechanisms by which IF are involved in the biology of cancer cells are still unclear. We found that site-specific phosphorylation of IF proteins induces the disassembly of filament structures. To further dissect the in vivo spatiotemporal dynamics of IF phosphorylation, we developed site- and phosphorylation state-specific antibodies. Using these antibodies, we detected kinase activities that specifically phosphorylate type III IF, including vimentin, glial fibrillary acidic protein and desmin, during mitosis. Cdk1 phosphorylates vimentin-Ser55 from prometaphase to metaphase, leading to the recruitment of Polo-like kinase 1 (Plk1) to vimentin. Upon binding to Phospho-Ser55 of vimentin, Plk1 is activated, and then phosphorylates vimentin-Ser82. During cytokinesis, Rho-kinase and Aurora-B specifically phosphorylate IF at the cleavage furrow. IF phosphorylation by Cdk1, Plk1, Rho-kinase and Aurora-B plays an important role in the local IF breakdown, and is essential for the efficient segregation of IF networks into daughter cells. As another part of our research on IF, we have set out to find the binding partners with simple epithelial keratin 8/18. We identified tumor necrosis factor receptor type 1-associated death domain protein (TRADD) as a keratin 18-binding protein. Together with data from other laboratories, it is proposed that simple epithelial keratins may play a role in modulating the response to some apoptotic signals. Elucidation of the precise molecular functions of IF is expected to improve our understanding of tumor development, invasion and metastasis. (Cancer Sci 2006; 97: 167,174) [source] | ||||||||||||||||||||||